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Pro109-2

CHLORIDE DIFFUSION AND BINDING IN HARDENED CEMENT PASTE FROM MICROSCALE ANALYSES



Author(s): Pietro Carrara, Laura De Lorenzis
Paper category: Proceedings
Book title: proceedings of the International RILEM Conference on Materials, Systems and Structures in Civil Engineering Conference segment on Service Life of Cement-Based Materials and Structures
Editor(s): Miguel Azenha, Ivan Gabrijel, Dirk Schlicke, Terje Kanstad and Ole Mejlhede Jensen
ISBN:978-2-35158-171-4
e-ISBN: 978-2-35158-173-5
Publisher: RILEM Publications SARL
Publication year: 2016
Pages: 543-552
Total Pages: 10
Language : English


Abstract: Chloride ions in concrete constitute a primary issue for the durability of concrete structures
because they can trigger the corrosion of the steel rebars. Chloride diffusion is strongly
influenced by the heterogeneous nature of the hardened cement paste (HCP) microstructure,
i.e. at a Pm length scale. HCP can be composed of more than 30 phases and only some of
them, typically AFm and CSH gel, can interact with chlorides influencing their diffusion (so-
called binding effect). To date, the direct observation of the HCP 3D microstructure and
phases arrangement is still a challenge. To overcome this problem, simulation codes such as
CEMHYD3D were developed to simulate the HCP hydration and microstructure development
making possible to distinguish between all the possible phases present. The chloride diffusion
into HCP is here studied through a novel diffusion model. The Fick’s theory is modified to
account for the binding effect phase-wise. A homogenization technique is adopted to upscale
the diffusivity at the mesoscale, namely where the HCP can be assumed homogeneous. Both
real and simulated HCP microstructures are used and their properties compared and related to
the chloride diffusive behavior. Also, comparisons between experimental and numerical
results from the proposed model are presented.


Online publication : 2016
Publication type : full_text
Public price (Euros) : 0.00


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